Rod coercer

ABSTRACT

A rod coercer for use in spinal fixation procedures is provided. The rod coercer can be pivoted in a first direction to fixedly grip an implant, and pivoted in a second direction to reduce a rod into the implant. In one embodiment, the rod coercer includes first and second articulating forceps branches, first and second rod contacting arms extending from the first and second forceps branches, and first and second implant gripping arms pivotally interconnected with the rod contacting arms. In another embodiment, the rod coercer includes forceps branches which each include upper and lower forceps branches which pivot with respect to each other, and a rod contacting arm interconnected with one of the forceps branches. In another embodiment, the rod coercer includes pivotable implant gripping arms and a rod contacting arm driven by one of the forceps branches.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to instruments for use in surgical applications, and more specifically, to a rod coercer for positioning a rod into a surgical implant during a spinal fixation procedure.

2. Related Art

In spinal fixation surgery, a rod and a set of vertebral implants (e.g., pedicle screws) are often used to correct spinal deformities. In such procedures, the rod is often bent to a desired shape using an appropriate rod bender. Then, a surgeon installs the implants in selected vertebral bodies along the length of the spine. Each implant usually includes a head which is shaped to receive a portion of the rod. After the implants have been installed, the rod is seated or “reduced” into the head of an implant, using a device which applies force to the rod and the implant, so that the implant and its associated vertebral body, and the rod, are drawn together, and a portion of the rod is seated in the head of the implant. Once the rod has been reduced into the head of the implant, a cap is engaged with (e.g., threaded into) the head of the implant and tightened to retain the rod in the head of the implant. This process may be repeated for each of the remaining implants, as needed, until the rod has been reduced into all of the implants. Once the procedure is complete, the spine conforms to the shape of the rod, to correct the spinal deformity. Thus, it is very important in such procedures to properly reduce a spinal rod into its associated implants.

Various devices for reducing a rod into an implant are known. One example is a simple forceps-type apparatus which includes articulating forceps branches and a bifurcated gripping nose which pivotally grips the head of an implant. When the forceps branches are closed and the pivotal grip is established, the device can be pivoted with respect to the implant to contact a rod and to exert force on same using a fulcrum arrangement, so as to reduce the rod into the head of the implant. Other devices include rod reducers having axially-aligned, concentric sleeves that move axially with respect to each other. Such devices include a pistol and trigger grip, as well as a ratchet mechanism interconnected with the trigger to urge one of the sleeves axially relative to another sleeve, causing prongs of the inner sleeve to grip an implant and the outer sleeve to reduce the rod into the implant. Another device includes a forceps-type instrument which grips an implant, and a separate articulating device which attaches to the forceps-type instrument and which pivots to reduce a rod into the implant.

SUMMARY OF THE INVENTION

The present invention relates to a rod coercer for use in spinal fixation procedures. The rod coercer includes first and second articulating forceps branches, first and second rod contacting arms extending from the first and second forceps branches, and first and second implant gripping arms pivotally interconnected with the first and second forceps branches. The forceps branches can be pivoted away from each other to open the implant gripping arms so that the arms can be positioned about the head of an implant and a rod to be reduced into the implant. The forceps branches can then be pivoted toward each other to clamp the implant gripping arms against the head of the implant, such that the head of the implant is fixedly gripped by the implant gripping arms. Optionally, corresponding locking tabs could be provided on the forceps branches for retaining the forceps branches and the implant gripping arms in a closed and locked position. After clamping the implant with the implant gripping arms, the forceps branches can be pivoted about the implant gripping arms so that the rod contacting arms contact the rod and the implant gripping arms draw the implant and the rod toward each other to reduce the rod into the head of the implant.

In another embodiment of the present invention, the rod coercer includes pivotally interconnected forceps branches, each of which is divided into upper and lower branch portions which are pivotally interconnected with each other so that the upper branch portion can be pivoted with respect to the lower branch portion. First and second implant gripping arms extend from the lower branch portions of the forceps branches. A rod contacting arm is provided, and is interconnected to an upper branch portion of one of the forceps branches by an upper linkage, and to a lower branch portion of the same forceps branch by a lower linkage. The forceps branches can be pivoted away from each other to open the implant gripping arms so that the arms can be positioned about the head of an implant and a rod to be reduced into the implant. The forceps branches can then be pivoted toward each other to clamp the implant gripping arms against the head of the implant, such that the head of the implant is fixedly engaged by the implant gripping arms. Optionally, corresponding locking tabs could be provided on the forceps branches for retaining the forceps branches and the implant gripping arms in a closed and locked position. After clamping the implant with the implant gripping arms, the upper branch portions can be pivoted with respect to the lower branch portions, so that the rod contacting arm contacts a rod and the implant gripping arms draw the implant and the rod together to reduce the rod into the head of the implant.

In another embodiment of the present invention, the forceps branches include first and second implant gripping arms which are pivotally interconnected with the branches, and a rod contacting arm coupled by gears to one of the forceps branches. An end of one of the forceps branches is attached to the face of a forceps gear, and an end of the rod contacting arm is attached to the face of an arm gear, such that the arm gear meshes with the forceps gear. The forceps branches can be pivoted away from each other to open the implant gripping arms so that the arms can be positioned about the head of an implant and a rod to be reduced into the implant. The forceps branches can then be pivoted toward each other to clamp the implant gripping arms against the head of the implant, such that the head of the implant is fixedly gripped by the implant gripping arms. Optionally, corresponding locking tabs could be provided on the forceps branches for retaining the forceps branches and the implant gripping arms in a closed and locked position. After clamping the implant with the implant gripping arms, the forceps branches can be pivoted with respect to the implant gripping arms, so that the forceps gear rotates the arm gear to pivot the rod contacting arm downwardly to contact the rod and the implant gripping arms draw the implant toward the rod to reduce the rod into the head of the implant.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention will be apparent from the following Detailed Description of the Invention, taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view showing the rod coercer of the present invention;

FIG. 2 is a partial perspective view showing the rod coercer of FIG. 1 in greater detail;

FIG. 3 is a partial front view showing the rod coercer of FIG. 1 in greater detail;

FIGS. 4A-4C are side views showing operation of the rod coercer of FIG. 1 to reduce a surgical rod into the head of an implant;

FIGS. 5A-5C are rear and side views of another embodiment of the rod coercer of the present invention, which includes pivotable upper and lower forceps branches and a rod contacting arm interconnected therewith;

FIGS. 6A-6C are partial rear, perspective, and side views of another embodiment of the rod coercer of the present invention, which includes pivotable implant gripping arms and a geared rod contacting arm;

FIG. 7 is a perspective view showing another embodiment of the rod coercer of the present invention, wherein integral rollers are provided at ends of the rod contacting arms and a retainer interconnects the implant gripping arms to maintain the arms in facing relationship; and

FIG. 8 is a perspective view of a cannula that can be used with the rod coercer of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a rod coercer for use in spinal fixation procedures. The rod coercer includes forceps branches which can be pivoted along a first arc (i.e., about a first axis) to fixedly grip the head of an implant, and which can be pivoted along a second arc (i.e., about a second axis) to reduce a rod into the head of the implant. By the terms “coerce” and “reduce,” it is meant the seating of a rod into a surgical implant through a mechanical application of force, such that the implant and the rod are drawn together and the rod is seated into the head of the implant.

FIG. 1 is a perspective view showing the rod coercer 10 of the present invention. The rod coercer 10 includes right and left forceps branches 12, 14 which are pivotally interconnected at a pivot point 16 (e.g., by a pin extending through and pivotally interconnecting the branches 12, 14, or any other suitable type of pivotable interconnection). The branches 12, 14 include finger loops 18, 20 for receiving an operator's fingers. Optionally, corresponding locking tabs 22 (which included mating inner surfaces having teeth) could be provided for maintaining the branches 12, 14 in a closed and locked arrangement. Rod contacting arms 24, 26, which contact a rod to reduce it into an implant, are provided at the ends of the branches 12, 14. Implant gripping arms 28, 30 are pivotally interconnected with the branches 12, 14. The implant gripping arms 28, 30 fixedly grip an implant 50 (which could be a screw (e.g., pedicle screw), hook, or any other suitable implant which is configured to receive a rod), while the arms 24, 26 pivot with respect to the arms 28, 30 to reduce a rod into the implant 50.

To grip the implant 50, the forceps branches 12, 14 are pivoted away from each other about a first axis (in the direction shown by arrow A), which causes both the implant gripping arm 28 to move away from the implant gripping arm 30, and consequently, the arms 24, 26 similarly move away from each other. The arms 28, 30 are then positioned about opposite sides of the implant 50, as well as about a rod (not shown in FIG. 1) to be reduced into the implant 50. The forceps branches 12, 14 are then urged toward each other in the direction shown by arrow A, by an operator's fingers applying force to the branches 12, 14, so that the arms 28, 30 fixedly clamp the implant 50 and, consequently, the arms 24, 26 are brought together. The arms 28, 30 each have inner surfaces which could be cylindrical in shape or could have any other shape configured to match the shape of the implant 50. The inner surfaces contact the sides of the implant 50 and are held in a fixed position against the implant 50 when the arms 28, 30 are clamped against the implant 50. The locking tabs 22, if provided, maintains the forceps branches 12, 14 and the arms 28, 30 in a locked configuration, such that the arms 28, 30 remain clamped against the implant 50 when the operator releases his or her grip on the rod coercer 10. Advantageously, this frees the surgeon's hand to perform other tasks (if desired or necessary) prior to reduction of a rod, as discussed below. When the arms 28, 30 are clamped against the implant 50, the forceps branches 12, 14 can pivot with respect to the arms 28, 30, in the direction shown by arrow B. As discussed below, this motion allows for reduction of a rod into the implant 50. Thus, the rod coercer 10 can be pivoted in a first direction (i.e., about a first axis) to fixedly grip the implant 50, and can be pivoted in a second direction (i.e., about a second axis) generally transverse to the first direction to reduce a rod into the implant 50.

FIG. 2 is a partial perspective view showing the rod coercer 10 in greater detail. As mentioned above, the arms 28, 30 are pivotally interconnected with the branches 12, 14. Such a pivotable interconnection could be provided by a first pin 32 inserted through the arm 30 and the branch 12, and a second pin 34 inserted through the arm 28 and the branch 14, as well as any other suitable type of pivotable interconnection between the arms 28, 30 and the branches 12, 14, such as screws having smooth (pin-like) portions on the shafts thereof about which the arms 28, rotate. The arms 28, 30 clamp opposite sides of the head 52 of the implant 50, and optionally include shoulders 36, 38. The space between the arms 28, 30 allows for insertion of a threaded cap, which could be threaded into the head 52 of the implant 50 to lock a rod to the implant 50, as well as an instrument for tightening such a cap.

FIG. 3 is a partial front view showing the rod coercer 10 in greater detail. The arms 24, 26 could include curved surfaces 40, 42 which could be shaped to receive the rod. This facilitates a proper interface between the arms 24, 26 as they bear against a rod during reduction of the rod into the implant 50. The shape of the curved surfaces 40, 42 could be varied to accommodate the geometry of the rod. It is noted that the arms 24, 26 need not extend at an angle to the branches 12, 14. Indeed, the arms 24, 26 could be parallel to the branches 12, 14. Additionally, the shapes and angles of the arms 24, 26 could be modified so that the arms 24, 26 can contact the rod at any desired location. It is also noted that a single arm could be provided for contacting the rod to reduce it into an implant.

The shoulders 36, 38, if provided, abut opposed upright walls 54, 56 of the head 52 of the implant 50 when the arms 28, 30 are clamped against the walls 54, 56 of the head 52. The shoulders 36, 38 help to prevent the rod coercer 10 from moving with respect to the implant 50 when the head 52 is clamped by the arms 28, 30. It is noted that the arms 28, 30 and walls 54, 56 could include complementary mechanical engagements (e.g., in the form of protrusions and corresponding recesses, etc.) which prevent movement between the arms 28, 30 and the implant 50 when the head 52 is clamped by the arms 28, 30. Such a protrusion is shown in FIG. 6B, discussed below, and could be provided in any desired geometry. The walls 54, 56 define a channel 58 into which a surgical rod is reduced by the arms 24, 26.

FIGS. 4A-4C are side views showing operation of the rod coercer 10 to reduce a surgical rod 60 into the head 52 of the rod 50. First, as shown in FIG. 4A, the arms 28, 30 of the rod coercer 10 are clamped against the head 52 of the implant 50 in the manner discussed above, such that the rod 60 is positioned between the arms 28, 30 and the arms 24, 26 are positioned above the rod 60. As can be seen, the implant gripping arms 28, 30 and the rod contacting arms 24, 26 define a first angle with respect to each other. Then, as shown in FIG. 4B, the forceps branches 12, 14 are pivoted in the direction shown by arrow B. This causes the arms 24, 26 to move downwardly in the direction shown by arrow C, so that the arms 24, 26 contact and exert force against the rod 60. As can be seen, when the branches 12, 14 are pivoted, a second angle (different than the first angle shown in FIG. 4A) is defined between the implant gripping arms 28, 30 and the rod contacting arms 24, 26. The implant 50 (and an anatomical structure, such as a vertebral body, in which the implant 50 is installed) is then moved upwardly toward the rod 60, as shown by arrow D. It is noted that the rod 60 could also be moved downwardly toward the implant 50, i.e., in a direction opposite the direction shown by arrow D. Thus, the arms 24, 26 operate as levers for moving the implant 50. Finally, as shown in FIG. 4C, the branches 12, 14 are further pivoted in the direction of arrow B, so that the arms 24, 26 are urged to a final position against the rod 60. In this position, the rod 60 is reduced into the head 52 of the implant 50, and a threaded cap or other type of locking device can be installed into the head 52 of the implant 50 to lock the rod 60 in position in the head 52. Once the rod is locked with respect to the implant 50 using a suitable locking device, the rod coercer 10 can be removed from the implant 50 by pivoting the forceps branches 12, 14 away from each other.

FIGS. 5A-5C are rear and side views of another embodiment of the rod coercer of the present invention, indicated generally at 100. The rod coercer 100 includes forceps branches 112, 114 which are pivotally interconnected and which can be pivoted with respect to each other, in the direction shown by arrow E. The branch 112 is divided into upper and lower branch portions 112 a, 112 b which pivot with respect to each other, and the branch 114 is divided into upper and lower branch portions 114 a, 114 b which pivot with respect to each other. Implant gripping arms 128, 130 are provided at the ends of the lower branch portions 112 b, 114 b for gripping opposite sides of the head 52 of the implant 50, and finger loops 118, 120 are provided at opposite ends of the branches 112, 114 for receiving an operator's fingers. The gripping arms 128, 130 can be brought together to clamp the head 52 of the implant 50 by urging the branches 112, 114 together in the direction of arrow E. Corresponding locking tabs 122 could be provided to lock the branches 112, 114 together, which locks the gripping arms 128, 130 against the head 52 of the implant 50. Upper and lower linkages 132 a, 132 b link a rod contacting arm 124 to the upper and lower branch portions 114 a, 114 b of the forceps branch 114. Of course, the linkages 132 a, 132 b could be attached to the upper and lower branch portions 112 a, 112 b of the forceps branch 112.

As shown in FIG. 5B, an upper end of the rod contacting arm 124 is pivotally interconnected to the upper branch portion 114 a by the linkage 132 a, such that the linkage 132 a is fixedly attached at one end to the upper branch portion 114 a and pivotally attached at an opposite end to the rod contacting arm 124. The lower end of the rod contacting arm 124 is linked to the lower branch portion 114 b by the linkage 132 b, such that the linkage 132 b is pivotally attached at one end to the lower branch portion 114 b and pivotally attached at an opposite end to the rod contacting arm 124. A curved surface 134 could be provided at the bottom of the rod contacting arm 124, which could be shaped to match the shape of the rod 60.

The upper and lower branch portions 112 a, 114 a and 112 b, 114 b are pivotally interconnected by a pivotable interconnection 136 provided in each branch 112, 114, which allows the upper branch portions 112 a, 114 a to pivot with respect to the lower branch portions 112 b, 114 b, as shown by arrow F in FIG. 5C. Such movement causes the rod contacting arm 124 to move downwardly in the general direction indicated by arrow G, so that the rod contacting arm 124 contacts the rod 60. This causes the implant 50 (and an anatomical structure in which it is installed, such as a vertebral body) to be drawn upwardly toward the rod 60, so as to reduce the rod 60 into the head 52 of the implant 50. It is also noted that the rod contacting arm could cause the rod 60 to move downwardly toward the implant 50 to reduce the rod 60 into the head 52 of the implant 50.

FIGS. 6A-6C are partial rear, perspective, and side views of another embodiment of the rod coercer of the present invention, indicated generally at 200. As shown in FIG. 6A, the rod coercer 200 includes branches 212, 214 which are pivotally interconnected via pivotable interconnection 216 and which can be pivoted with respect to each other, in the direction of arrow H. Upper ends of the branches 212, 214 could include finger loops and, optionally, locking tabs, such as the finger loops and locking tabs shown in the previous embodiments. Implant gripping arms 226, 228 are provided for gripping opposite sides of the head 52 of the implant 50, and can be brought together to clamp the head 52 of the implant 50 by urging the branches 212, 214 together in the direction of arrow H.

As shown in FIG. 6B, the implant gripping arms 226, 228 are pivotally interconnected with the branches 212, 214 via joints 230, 232. The joint 230 is formed by a collar 250 attached to an end of the branch 212, which pivots about a pin 252 extending through the upper portion of the gripping arm 226. The joint 232 links a rod contacting arm 234 to the forceps branch 214. The branch 214 is attached to a face of a forceps gear 242, and the rod contacting arm 234 is attached to the face of an arm gear 240, both of which gears 240, 242 intermesh. The gears 240, 242 rotate about pins 244, 246 inserted into an upper end of the implant gripping arm 228. Thus, both the forceps branch 214 and the rod contacting arm 234 pivot at adjacent pivot points in joint 232.

Optionally, protrusions 248 could be provided on the rod contacting arms 226, 228 for insertion into corresponding recesses formed on an implant. The geometry of such protrusions could be varied as desired. Also, the rod contacting arm 234 could be bent (as shown in FIG. 6B) or provided in any desired shape or geometry. Additionally, a curved surface 236, shaped to match the shape of a rod, could be provided on the rod contacting arm 234.

As shown in FIG. 6C, when the branches 212, 214 are pivoted in the direction of arrow I, the forceps gear 242 rotates. This causes the arm gear 240 to rotate, which causes the rod contacting arm 234 to pivot in the direction of arrow J, so that the surface 236 contacts the rod 60. This causes the implant 50 (and an anatomical structure (e.g., a vertebral body) into which the implant 50 is installed) to be drawn upwardly toward rod 60 by the implant gripping arms 228, 230, as indicated by arrow K, so that the rod is reduced into the head 52 of the screw 50. It is noted that the rod 60 could also be urged downwardly toward the screw 50 to reduce the rod 60 into the head 52 of the screw 50.

FIG. 7 is a perspective view showing another embodiment of the present invention, which is similar in construction to the rod coercer shown in FIGS. 1-4C. In this embodiment, integral rollers 352, 354 are provided on ends of the rod contacting arms 324, 326, which roll along a rod as it is reduced. The rollers 352, 354 reduce friction between the rod and the arms 324, 326, thereby reducing the amount of force required to reduce a rod. Also provided is a flexible retainer 356 interconnecting the implant gripping arms 328, 330. The retainer 356 allows the arms 328, 330 to be maintained in facing relationship with each other as they are pivoted with respect to forceps branches 312, 314. Also, the retainer 356 stretches (as shown by arrow L) so that the arms 328, 330 can be spread apart by manipulating the forceps branches 312, 314. As such, the retainer 356 does not interfere with operation of the rod coercer. The rollers 352, 354 could be provided on the rod contacting arms of each of the embodiments of the rod coercer disclosed herein, and the flexible member 356 could be provided for interconnecting the implant gripping arms of each embodiment of the rod coercer disclosed herein.

FIG. 8 is a perspective view showing a cannula (guide tube) 400 which could be utilized with each embodiment of the rod coercer of the present invention. The cannula 400 could be positioned between the implant gripping arms of the present invention to guide a set screw and an associated tightening tool for locking a rod into an implant. The shape and size of the cannula 400 could be modified as desired without departing from the spirit or scope of the present invention. It is also noted that the cannula 400 could be threadably, frictionally, or otherwise engaged with the implant gripping arms of the present invention (e.g., using corresponding interlocking protrusions/recesses to lock the cannula 400 to the arms).

Having thus described the invention in detail, it is to be understood that the foregoing description is not intended to limit the spirit or scope thereof. What is desired to be protected is set forth in the following claims. 

What is claimed is:
 1. A rod coercer, comprising: first and second forceps branches, each of said first and second forceps branches including pivotally interconnected upper and lower branch portions, said upper branch portion pivotable with respect to said lower branch portion; first and second implant gripping arms extending from said lower branch portions of said first and second forceps branches; a rod contacting arm linked to said upper and lower branch portions of one of said first and second forceps branches; and first and second linkages interconnecting said rod contacting arm to said upper and lower branch portions, wherein said first and second forceps branches are pivotable about a first axis to clamp said first and second implant gripping arms in fixed positions against the implant, and said upper portions of said first and second forceps branches are pivotable about a second axis different from the first axis to urge the rod contacting arm against a rod to reduce the rod into the implant.
 2. The rod coercer of claim 1, wherein said first linkage is fixedly attached at one end to an upper branch portion and pivotally attached at an opposite end to said rod contacting arm.
 3. The rod coercer of claim 2, wherein said second linkage is pivotally attached at one end to a lower branch portion and pivotally attached at an opposite end to said rod contacting arm.
 4. The rod coercer of claim 1, wherein said rod contacting arm includes a curved surface for receiving the rod.
 5. The rod coercer of claim 1, further comprising a roller attached to said rod contacting arm for rolling along the rod.
 6. The rod coercer of claim 1, further comprising a cannula positioned between said first and second implant gripping arms.
 7. The rod coercer of claim 1, further comprising a retainer interconnecting said first and second implant gripping arms for maintaining said first and second implant gripping arms in facing relationship.
 8. A rod coercer, comprising: first and second pivotally interconnected forceps branches; first and second implant gripping arms pivotally interconnected with said first and second forceps branches; a rod contacting arm pivotally interconnected with one of said first and second implant gripping arms and driven by one of said first and second forceps branches; a forceps gear attached to one of said first and second forceps branches; and an arm gear attached to said rod contacting arm, said forceps gear driving said arm gear to pivot said rod contacting arm when said first and second forceps branches are pivoted, wherein said first and second forceps branches are pivotable about a first axis to clamp said implant gripping arms against the implant, said first and second forceps branches are pivotable about a second axis different from the first axis to urge said rod contacting arm against the rod to reduce the rod into the implant.
 9. The rod coercer of claim 8, wherein said rod contacting arm includes a curved surface for receiving the rod.
 10. The rod coercer of claim 8, further comprising a roller attached to said rod contacting arm for rolling along the rod.
 11. The rod coercer of claim 8, further comprising a cannula positioned between said first and second implant gripping arms. 